The surface state of nanocrystalline and amorphous Mg2Ni alloys prepared by mechanical alloying

Amorphous (Mg1-xZrx)(2)Ni alloys with the composition of x=0.1 and 0.3 were synthesized by mechanical alloying (MA). A nanocrystalline Mg2Ni phase was also formed by MA without Zr addition. X-ray photoelectron spectroscopy (XPS) was used to investigate the atomic bindings of the alloying elements at the electrode surface. The analysis of the XPS of Mg Ip spectra showed that the atomic binding of Mg at the amorphous or nanocrystalline surface was lower than at the crystalline one. However, the Ni 2p spectra showed little variation in the amorphous or nanocrystalline phase compared to the crystalline. The looser binding of Mg at the surface indicates that the surface energy of the amorphous or nanocrystalline electrode was increased, and the hydrogen diffusion and charge transfer reaction enhanced. A passive layer of Mg(OH)(2) and rapid degradation of the electrode were also caused by the looser binding of Mg. (C) 2000 Elsevier Science B.V. All rights reserved.